Biology & Life Science Made Simple: Cells, Body, Nutrition & Plants (RRB NTPC)
A from-scratch, exam-focused tour of Class 10 biology for RRB NTPC — the cell and its parts, the main human body systems, vitamins and deficiency diseases, common diseases and their causes, and basic plant biology like photosynthesis and transport. Packed with tables, a worked example and quick-revision facts.
By the PadhoDost Team · 📖 8 min read · Updated 4 August 2026
Part of Railway Exams (RRB) prep🧠 One brick, one whole building
Imagine Howrah station built from lakhs of tiny bricks. Remove the bricks and there is no station at all. Living things work the same way: every plant and animal is built from microscopic 'bricks' called cells. Just as a strong building needs healthy bricks, a healthy body needs healthy cells doing their jobs. In this lesson we travel from a single cell to the whole body, then to food, diseases and plants — the exact mix RRB NTPC loves. Padho, dost!
The Cell — Where Life Begins
Every living thing — a mango tree, an ant, or you — is made of tiny units called cells. The cell is the basic building block of life, which is why we call it the 'structural and functional unit of life': it gives the body its structure and carries out life's jobs. Robert Hooke first saw and named cells in 1665 while looking at a thin slice of cork under his microscope. The Cell Theory sums it up in three lines: all living things are made of cells, the cell is the basic unit of life, and every new cell comes from a pre-existing cell.
| Cell part | Main job |
|---|---|
| Nucleus | Control centre of the cell; holds DNA |
| Mitochondria | Powerhouse; releases energy (ATP) |
| Ribosome | Site of protein synthesis |
| Chloroplast | Does photosynthesis (plant cells only) |
| Cell wall | Gives rigid shape and support (plant cells only) |
| Vacuole | Stores water, food and waste (large in plant cells) |
The Human Body and Its Systems
Your body runs like a well-coordinated railway network, with different departments handling different jobs. The digestive system breaks down food, the respiratory system takes in oxygen and removes carbon dioxide, the circulatory system pumps blood, the nervous system carries messages, and the excretory system removes waste. All of them work together every second to keep you alive.
Body facts worth memorising
- ✓An adult human body has 206 bones; a newborn baby has around 300.
- ✓The heart has 4 chambers and pumps blood all around the body.
- ✓Skin is the largest organ; the liver is the largest internal organ.
- ✓The smallest bone (stapes) is in the ear; the longest bone (femur) is in the thigh.
- ✓Normal body temperature is about 37 degrees Celsius (98.6 degrees Fahrenheit).
- ✓Red blood cells carry oxygen using the red pigment haemoglobin.
Nutrition, Vitamins and Deficiency Diseases
| Vitamin | Chemical name | Deficiency disease |
|---|---|---|
| Vitamin A | Retinol | Night blindness |
| Vitamin B1 | Thiamine | Beriberi |
| Vitamin C | Ascorbic acid | Scurvy |
| Vitamin D | Calciferol | Rickets |
| Vitamin K | Phylloquinone | Poor blood clotting |
📝 Cracking a deficiency question
Question: A person cannot see clearly in dim light after sunset. Which vitamin is likely missing?
Step 1 — Name the symptom: poor vision in low light is called night blindness.
Step 2 — Recall which vitamin protects the eyes: Vitamin A (retinol).
Step 3 — Match it: night blindness is the classic sign of Vitamin A deficiency.
Step 4 — Food fix: carrots, papaya, spinach and milk are rich in Vitamin A.
Answer: The missing nutrient is Vitamin A.
Diseases and What Causes Them
| Disease | Caused by | Spread by / note |
|---|---|---|
| Malaria | Protozoan (Plasmodium) | Bite of female Anopheles mosquito |
| Dengue | Virus | Bite of Aedes mosquito |
| Tuberculosis (TB) | Bacteria | Air — coughing and sneezing |
| Cholera | Bacteria | Contaminated water and food |
| Rabies | Virus | Bite of an infected animal |
Plant Biology Basics
Green plants make their own food by photosynthesis in the leaves, using sunlight trapped by the green pigment chlorophyll. To move materials around, plants use two pipe-like tissues: xylem carries water and minerals upward from the roots, while phloem carries the food (sugar) made in the leaves to the rest of the plant. The loss of extra water as vapour from leaves through tiny pores called stomata is known as transpiration.
⚡ Quick check
Which of these diseases is caused by a virus and NOT by bacteria?
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